A radar device radiates radio waves which are generated based on a radar transmission signal from a measurement point to a space, receives a reflected wave signal from a target, and measures at least one of the distance between the measurement point and the target, the position of the target and direction of the target. In recent years, particularly, a multiple-input multiple-output (MIMO) radar device has been developed in which a transmission-side system and a reception-side system each use a plurality of antennas.
In the MIMO radar device, the transmission-side system transmits the radar transmission signals from a plurality of antennas substantially at the same time and the reception-side system separately receives the radar transmission signals, which are reflected waves from the target, using a plurality of antennas. According to the MIMO radar device, since the radar transmission signals are transmitted from a plurality of antennas substantially at the same time, it is possible to reduce the time required to measure the target.
There is a MIMO radar device which receives a reflected wave signal from the same target through a plurality of different paths. Therefore, when propagation fading occurs, it is possible to improve the detection accuracy of a target and a sensing distance based on a diversity effect.
For example, Non Patent Literature 1 discloses as an example of the MIMO radar device according to the related art. In the MIMO radar device according to the related art, a transmission-side system transmits each radar transmission signal multiplied by orthogonal code sequences which are orthogonal to each other from a plurality of antennas at the same time. In the MIMO radar device according to the related art, a reception-side system multiplies each signal received by a plurality of antennas by an orthogonal code sequence orthogonal to the orthogonal code sequence used in the transmission-side system to separate each reception signal. According to the MIMO radar device of the related art, it is possible to reduce the time required to measure a target.